The acute hormonal and amino acid responses to differing food substrates were examined in type 1 glycogen storage disease. Ingestion of a glucose load or a glucose-plus-beef meal caused an acute fall in the initially elevated plasma glucagon, alanine, proline, and lactate. Ingestion of beef alone caused a sharp rise in these parameters. Long term nocturnal intragastric therapy of a high carbohydrate and moderate amino acid content resulted in a similar fall in these parameters as well as a fall in the elevated plasma glutamate, uric acid, triglycerides, and RBC-reduced glutathione. A remarkable clinical improvement and growth spurt accompanied the improvement in these biochemical values. The possible relation between the disturbed plasma hormonal and amino acid findings and growth failure and hyperuricemia is discussed.